> ## Documentation Index
> Fetch the complete documentation index at: https://companyname-a7d5b98e-cex-integration-docs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Library cells

Library cells allows to extend deduplication mechanism on-chain. This significantly reduces the size of serialized data
and enables efficient storage of incrementally updated data. For the details see [library cells page](/ton/cells/library-cells).
Always has level zero, so does not contain any higher hashes.

Each library cell is serialized as follows:

* The 1-byte tag that always equals to `0x02`.
* The 256-bit [representation hash](/tvm/serialization/cells) of the library cell being referred to.